Laserfiche WebLink
<br />was jUBt outside the north end o,f the existing levee. The <br />adjustm~nt to the floodway did not. cause the difference in water <br />surface elevations between nonflood.,ay and floodway conditions to <br />increas~. The west levee extension would be located completely <br />outside the floodway. No adjustmen't of' the floodway boundary would <br />be need~d. <br /> <br />Effect of Ice on Hvdraulic Analyses <br /> <br />The hydraulic analyses described previously were also computed <br />for ope:t-flow conditions, with no effects from ice. An analysis of <br />ice-jam flooding was not part of 1:he scope of this study. In <br />general, ice jams may cause increas.ad water surface elevations that <br />approach or exceed those from open-.water floods having much higher <br />discharges. The results of the hydraulic analyses show 1:hat, even <br />without ice jams, the larger open-water flood events, such as the <br />100-year event, would cause extensive flooding at Rangely. <br /> <br />GENERAL LEVEE IlEQUIREMENTS <br /> <br />Fer purposes of the NFIP, FEMA will only recognize those levee <br />systems that meet, and continue to meet, minimum desiqn and <br />operation and maintenance criteria. 'I'hese criteria are identified <br />in the Code of Federal Regulations (44 CFR 65.10). The <br />requirements are in the areas of freEaboard, closures, s'tructural <br />design, interior drainage, and ope,ration and maintenance.. The <br />levee systems must be certified accordinq to 44 CFR 6!5.10e. The <br />requirements are discussed in the fOllowing paragraphs. <br /> <br />Freeboard <br /> <br />Levees must provide a minimum of 3 feet of freeboard above the <br />water surface level of thE~ base (IOo-year) flood. An additional <br />I foot above the minimum is required within 100 feet on either side <br />of structures such as bridges or whe,rE!ver the flow is const:ricted. <br />An additional one-half foot is requirE~d a.t the upstream end of the <br />levee. <br /> <br />12 <br />